1. Field of the Invention
This invention relates to motion controllers used to control multiple step motors and/or servos in coordinated multi-axis motion. The invention particularly relates to motion controllers with digital signal processors in standalone and multiprocessor implementations which use serial input and output for at least some controlled functions. The present invention also relates to a lid dispensing and application arrangement which may be controlled by the motion controller of the present invention.
2. Description of Related Art
Motion controllers are widely used to control various types of automated machinery and material handling equipment. By way of example, the motion controller disclosed herein is suited for controlling the automated drink mixer system described in U.S. Pat. No. 5,000,345.
The functioning of a motion controller may generally be divided into the motor control aspect, wherein multiple motors/servos are driven in coordinated motion to move an object along a defined trajectory, and the input/output aspect wherein input and output data are sent to and from various sensors and actuators.
A simple example of input data would be the signal from a location sensor which is triggered by a light sensor or a microswitch position sensor indicating that material being handled had reached a known location. An example of output data would be a signal turning on an indicator light on a control panel or operating a relay to release an object for subsequent handling by the motors.
To provide the motor control, the motion controller must often perform intensive signal processing calculations. To provide multiple motor control, these calculations may tax the capabilities of the processor performing them, even where the processor is a digital signal processor (DSP), which is optimized for such tasks. To provide the I/O functions, data handling, memory accessing and other more generalized computer functions are used.
In prior art designs, the I/O, data handling and control functions have generally been implemented in a general purpose microprocessor. The digital signal motor control calculations have often been given to a dedicated digital signal processor which operates as a slave to the general purpose microprocessor. This solution is expensive, as it employs multiple processors. Some multiple processor designs have used a single DSP for each motor or a single DSP for each trajectory being calculated.
Many prior art motion controllers have been dedicated to particular tasks and are designed for use with specific equipment. They have usually included multiple inputs and outputs assigned to various tasks. One output might control a specific relay or a specific type of relay. An input might be designated to receive encoder data, while another input might be for a sensor. The number of specific inputs and outputs has made it difficult to fit all the connectors onto a single panel.
The variety of drivers, buffers, translators and other associated electronics for the motor and I/O inputs and outputs has made such controllers ill suited for use with anything other than the equipment for which it was originally designed.
The present invention provides improvements in both the motor control area and in the input/output system by optimizing the use of a digital signal processor for use in those tasks where it is required, in combination with a serial I/O system that offloads various housekeeping, memory addressing and control functions from the DSP.
The DSP may be operated in a standalone mode in the majority of applications to control multiple motors and multiple trajectories simultaneously with good response on all axes.
The input/output system of this invention has been implemented serially which permits the application specific electronics associated with driving outputs and formatting input data to be placed in remote digital I/O locations near the motors and I/O sources. This lets the motion controller function in numerous applications, and only the electronics for a particular application needs to be supplied in the customized digital input/output systems. Unused electronics for other applications is avoided without compromising flexibility in the controller.
A further advantage is that input/output conversion can be done at remote digital I/O units, near the source, instead of at the controller. This minimizes the possibility of errors being introduced in long cable runs from the controller.
In many prior art designs, the input data and output data is processed by the microprocessor which involves a significant waste of processor time through the overhead involved in addressing and moving the input/output data to and from memory. Accordingly, one object of the present invention is to provide a low cost motion controller in which the digital signal processor operates in a standalone mode.
A further object of the present invention is to provide a design in which input/output data is transmitted serially to remote input/output devices.